The death toll from Hong Kong’s worst fire in its peacetime history has risen to at least 44, authorities have said, with hundreds of others still unaccounted for.

Hong Kong leader John Lee confirmed the updated death toll early on Thursday, a day after flames tore through an eight-building apartment estate in the northern part of the Chinese city.

Lee told reporters that at least 279 people were still missing, while 29 had been hospitalised, including seven who were in a critical condition.

Firefighters worked into the night, as thick, black smoke billowed from the 31-storey towers and orange flames lit up the sky at the Wang Fuk Court estate in the Tai Po district.

Derek Armstrong Chan, deputy director of fire services, told a news conference on Thursday that darkness overnight had hampered their operations and firefighters were still having difficulty accessing two of the buildings.

“Up to this moment, the temperature inside the fire scene is still very high,” Chan told reporters.

Chan earlier told reporters that firefighters had struggled to respond to residents’ pleas for help, with falling debris and scaffolding posing a danger to front-line personnel.

Hong Kong’s Fire Services Department said that nine people had been declared dead at the scene.

Local media reported that some residents were believed to be trapped inside their homes.

Police said they arrested three men on suspicion of manslaughter in connection with the fire, without providing details of their alleged wrongdoing.

The fire is Hong Kong’s deadliest blaze since World War II, when Japanese forces occupied the then British-ruled territory.

Before Wednesday’s blaze, the fire at the 1996 Garley Building in Kowloon had ranked as the worst fire in peacetime, with 41 lives lost.

The fire department on Wednesday upgraded the blaze to a level five alarm – the most severe grade.

“There’s nothing that can be done about the property. We can only hope that everyone, no matter old or young, can return safely,” a Tai Po resident surnamed So, 57, told the AFP news agency near the scene of the fire.

“It’s heartbreaking. We’re worried there are people trapped inside.”

Reporting from Tai Po on Wednesday, journalist Laura Westbrook told Al Jazeera that when the fire started, it spread through bamboo scaffolding that was affixed to the buildings in the housing estate.

Frames of scaffolding were seen tumbling to the ground as firefighters battled the blaze, while scores of fire engines and ambulances lined the road below the development, witnesses told Reuters.

“As I’ve been standing here, I can smell the smoke, and occasionally we hear these pops as some of the debris falls to the ground,” Westbrook said.

Wang Fuk Court is one of many high-rise housing complexes in Hong Kong, one of the most densely populated areas in the world.

Harry Cheung, 66, who has lived at Block Two in one of the complexes for more than 40 years, said he heard “a very loud noise” at about 2:45pm local time (06:45 GMT) and saw a fire erupt in a nearby block.

“I immediately went back to pack up my things,” he told the Reuters news agency. “I don’t even know how I feel right now. I’m just thinking about where I’m going to sleep tonight, because I probably won’t be able to go back home.”

Dozens of ambulances, fire trucks

People had gathered on a nearby overhead walkway, watching in dismay and taking pictures as smoke billowed from the buildings.

Firefighters deployed 128 fire trucks and 57 ambulances to the scene.

Meanwhile, authorities set up a casualty hotline and opened two temporary shelters in nearby community centres for evacuated residents. Sections of a nearby highway were also closed by the firefighting operation.

“Residents nearby are advised to stay indoors, close their doors and windows, and stay calm,” the Fire Services Department said in a statement on Wednesday. “Members of the public are also advised to avoid going to the area affected by the fire.”